Formation of aliphatic and aromatic alpha-hydroxy ketones by Zygosaccharomyces bisporus

The wild-type yeast strain Zygosaccharomyces bisporus CBS 702 produced alph a-hydroxyketones (acyloins) from amino acid precursors after transamination to the corresponding 2-oxo acids. The key enzyme of the subsequent decarbo xylation and C-C bond forming reaction, pyruvate decarboxylase (PDC), was e xamined for its substrate- and stereo-specificity. A wide variety of satura ted and unsaturated aliphatic and aromatic aldehydes was successfully conve rted to acyloins. 19 of the biotransformation products identified had not b een reported as natural substances before. Product yields were strongly aff ected by substrate structure.